Study of the spontaneous retinal degeneration affecting Osborne-Mendel and spontaneously hypertensive Wistar rats ((SHR) has been hampered by the lack of suitable control animals. However, further examination of the Wistar colony which serves as a non-hypertensive control for the SHR indicates a much lower incidence of retinal degeneration. Animals from these strains are being compared with regard to their susceptibility to light-induced photoreceptor destruction.